Question

so I wrote a program and I want to pass it either a filename and an integer or just an integer. Whats the best way to determine which argument is the integer? This is what I have:

import sys

if len(sys.argv) > 1):
    for e in sys.argv:
        try:
            bio = map(e, int)
        except:
            pass

thanks in advance

Answer 1

You could check whether or not the argument is an integer with the string isdigit() method:

import sys

if len(sys.argv) > 1:
    for e in sys.argv:
        if e.isdigit():
            # all characters in e are digits and there is at least one character in e
        else:
            # it is possibly your filename argument

But, I should encourage you to give a chance to the argparse library: http://docs.python.org/dev/library/argparse.html

import argparse
parser = argparse.ArgumentParser(description = 'A simple description')

parser.add_argument('-f', action = 'store', dest =  'filename', required = False)
parser.add_argument('-n', action = 'store', dest = 'n', required = True, type=int)

arguments = parser.parse_args()

print arguments.n
print arguments.filename